ZR-1 Net Registry Forums - View Single Post

Aurora40 · 07-19-2009

Right, doesn't the MAP just indicate how well the air filter and TB are working to keep air going into the motor? Maybe we're saying the same thing and I'm misunderstanding you, or maybe I've got it wrong (again)?

If you are seeing the MAP pressure drop above 5800 rpm, doesn't that mean your intake system (TB, air filter, duct, etc) is not able to keep up with the consumption rate of the motor? Ideally wouldn't it be the case that the MAP would not drop as RPMs increase?

It sounds like what you describe is what I see. As RPM increases, the MAP reading drops fairly linearly. But VE doesn't drop in the same way. At 1,500 rpm, the engine has worse VE than at 4,500, correct? At 1,500 rpm at WOT, the MAP reading will definitely be higher or as high as at 4,500.

Also, the MAP is not differential, it is an absolute pressure measurement, isn't it? For example, the sensor can differentiate between a day with high ambient pressure vs a day with low ambient pressure, can't it?

Sorry for all the questions, I'm just trying to understand.

07-19-2009	#13
Aurora40 Join Date: May 2005 Location: Leesburg, VA Posts: 2,704	Re: Need help understanding scan data Right, doesn't the MAP just indicate how well the air filter and TB are working to keep air going into the motor? Maybe we're saying the same thing and I'm misunderstanding you, or maybe I've got it wrong (again)? If you are seeing the MAP pressure drop above 5800 rpm, doesn't that mean your intake system (TB, air filter, duct, etc) is not able to keep up with the consumption rate of the motor? Ideally wouldn't it be the case that the MAP would not drop as RPMs increase? It sounds like what you describe is what I see. As RPM increases, the MAP reading drops fairly linearly. But VE doesn't drop in the same way. At 1,500 rpm, the engine has worse VE than at 4,500, correct? At 1,500 rpm at WOT, the MAP reading will definitely be higher or as high as at 4,500. Also, the MAP is not differential, it is an absolute pressure measurement, isn't it? For example, the sensor can differentiate between a day with high ambient pressure vs a day with low ambient pressure, can't it? Sorry for all the questions, I'm just trying to understand. Last edited by Aurora40; 07-19-2009 at 04:40 PM.